In network switching systems, switching fabrics and network processors are interconnected to support the media speed data stream of the network links in up and down directions. The up-network processor receives the network data flow from its input ports to the network links, identifies and process the data units and send them as an internal data flow to an internal address of the switching system. This internal address can be a switching fabric or one other component of the switching system. The down-network processor receives the internal data flow, processes this data flow and send it as network data units to its output ports to the network links. In the split of tasks characterizing the switching systems, the network processor is responsible for supporting the different network protocols such as ATM, IP, IPX, Packet Over SONET, Ethernet and Frame Relay.
The race to the best cost/performance ratio leads the network component manufacturers to have the most scalable and flexible switching systems. An ideal flexible and scalable switching system starts from the minimum set of functions and hardware for control and switching; ideally, this minimal configuration should be upgradable to a highly sophisticated switching system having, in terms of control ISO Layer 2 to 7 implemented, and in terms of switching capacities a high throughput. In a traditional switching box configuration including switching blades and network interface blades, the price per port is lower if the user can limit the number of network interface blades; high density network interface blades, and thus network processors, should increase their density.
The scalable Rapacity in a network switching system may depend on the scalable capacity of the switch fabric itself; the IBM/Es scalable switching technology is based today on PRIZMA switch, more particularly the recently available PRIZMA-E which provides the port expansion function. At the time of this writing, further information is available at: http://www.zurich.ibm.com/Technology/ATM/SWOCPWP/WWW.
The scalable capacity in a network switching system may depend on the scalable capacity of the network processor, independently of the switching fabric. As an illustration of the independence expected for the network processor is the fact that it should be able to interface any switching fabric using, for instance, the emerging standardized interface, CSIX. The network processor should provide a scalable density independently to the scalable capacity of the switch fabric itself When the network processor increases its density, providing more and more network ports, the switch is only required to sustain the increasing throughput. Furthermore, some switching configurations could even not involve a switch fabric but only interconnected network processors. On the other side, in a large switching system, the number of switching fabrics should be increased for improving the switched throughput or for bringing reliability in redundant switching configurations.
All these requirements on the switching systems implies that the up-interface of network processors be able to sustain all types of configurations which cannot be found in the network components manufacturer industry today.